TOPIC: Sound warble

My analog began sounding like crap a few days ago. DTS is fine. I noticed it when the trailer ROBOTS played and it wasn't on the dts trailer disk I was using.

I have an Component Engineering ASR-40, that is about six months old. If I got a manual or trouble-shooting guide with it, it got destroyed in the fire. Is there any routine maintenance that is supposed to be done to these? Do the heads require cleaning?

Watch the sound drum after the film runs out through the projector. Its inertia (large flywheel) should allow it to continue to rotate for many seconds after the film runs out. Rotate it by hand and see if there is any sticking. Be sure you are threading the film over the sound drum with the correct tension.

"Warble" is sometimes called "Wow and Flutter", and is especially noticeable in sustained musical notes, especially piano or violin. It is caused by minute variations in the film speed as it travels through the sound reader. Warble would not be related to "white light" or red LED reader differences.
John P. Pytlak, Senior Technical Specialist
Customer Technical Services
Entertainment Imaging
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It's an RCA 9030. We changed out the bearings today and that didn't fix it. My projectionist did discover that the film is loose when it passes the sound drum. He is going to change the spring tomorrow and see if that fixes the problem.

Thanks for the responses guys. We do leave the proper amount of slack in that loop. The sound is a definite warble. We will check the nut and tension spring on the back of the flywheel and the lateral guide roller assembly today.

The sound drum is essentially a flywheel which serves to keep the film running through the light beam at constant speed and smoothly, so anything which interferes with that can cause your warble... Ken's suggestion to check the lateral guide roller for problems seems the most likely spot to suspect... Even minor flat spotting will make the film jumpy...

One other issue with older simplex and RCA soundhead that luckily wasn't the issue here
but worth noting
they have a flywheel that is actually a flywheel inside a shell that has a viscus oil solution that couples the two togather and then to the shaft
If they get dinted then mechanical coupling occurs and then they can just go in the dumpster also if any foreign dirt or grit gets in them since there is onlya few thousanths of an inch clearnace between the outer casing and the actual drum will cause flutter as well
treat them with lots of respect